In the field of artificial membrane lungs, silicone rubber is used as a membrane due to its excellent gas permeability and good blood compatibility. The most serious drawbacks to the use of such lungs for long-term extracorporeal perfusion, are bleeding related to anti-coagulation and perfusion anemia. Standard silicone rubber (SSR) presently used in membrane lungs as shown in the patent to Kolobow (U.S. Pat. No. 3,489,647), however, contains silica filler.
In KOLOBOW '647 there is disclosed an artificial organ for membrane dialysis of biological fluids. Exemplified are an artificial lung and an artificial kidney, as well as processes for carrying out the functions of these artificial organs. A generic process is disclosed of adding to or removing from a body fluid (e.g., blood) a biologically active material (e.g., impurities in the blood normally released to the lungs or the kidneys) by dialysis through a membrane wherein the body fluid is passed over one side of a permeable membrane and the biologically active material diffuses through the membrane.
Substantially defect-free organo polysiloxane films are known as shown in the patent to Robb (U.S. Pat. No. 3,325,330) the specification of which discloses a process for making such films. However, Robb discloses some filler material used with a lower limit of 0.1 parts of filler per one part of organo polysiloxane by weight. The patent to Robb does not indicate that such substantially defect-free organo polysiloxane films may have a better blood compatibility than SSR blood contacting surfaces.
Similarly, the Gajewski et al U.S. Pat. No. 3,759,788 discloses an organic plastic material for use in improving the antithrombogenic characteristics of artificial kidneys and other organ perfusion devices. The disclosure of Gajewski et al indicates that fillers are a contemplated ingredient of their organic plastic and in the examples shown finely divided silica filler is used.